1. Field of the Invention
The present invention relates to an image processing apparatus which performs a rotating process at a specified angle on the image data entered into it and forms image data as processed for rotation thereof on a page memory device.
2. Description of the Related Art
A conventional image processing apparatus which is capable of executing a rotating process on entered image data at an angle corresponding to an integral number of times of 90 degrees at a high velocity is taught in Japanese Patent Unexamined Publication No. Hei. 5-108812. FIG. 17 is a block diagram illustrating an outline of the construction of the conventional image processing apparatus, which processes as one block the sequentially entered image data for a number of lines in accordance with the ratio of the bit width per one pixel indicating the number of tonal ranges of one pixel (hereinafter referred to as an image structure) and the bit width per one word in a page memory device 300 for putting out the image data as processed for a rotation thereof and writing alternately to two buffer memory devices 207 and 208 by the above-mentioned block as the unit.
Then, the image processing apparatus sequentially reads the image data for one block as written to the buffer memory devices 207 and 208 from the reading addresses generated by a buffer memory reading control unit 212 in accordance with the angle of rotation and generates the data for one word in the page memory device 300 by performing a rearrangement and a rotating process at a specified angle on the data thus read out. Then, by writing the word data to an address in the page memory device 300 as calculated in accordance with the specified angle of rotation, the image processing apparatus is capable of performing a rotating process as indicated on the sequentially entered image data and developing the image data on the page memory device 300.
Now, more and more intensive development work has been carried out in recent years on an image processing apparatus which, being used in a single unit, is capable of processing a plural number of types of image data different in image structure, such as a case of a multi-function equipment having the functions of a copying machine, a printer, and a facsimile machine integrated in one unit or a multi-media processing equipment, and it is therefore required of a single unit of such an image processing apparatus built in such an equipment to be capable of performing an image data rotating process on a plural number of types of image data different in image structure.
However, the image processing apparatus disclosed in Japanese Patent Unexamined Publication No. Hei. 5-108812 is not capable of fulfilling the above-mentioned requirement since the image structure of the image data which the image processing apparatus takes up as an object of an image rotating process is limited to one type because the width of the data written to the buffer memory devices 207 and 208 and the width of the data read out of the same buffer memory devices are determined by the image structure.
In contrast with this, it is conceivable to provide a device for performing a rotating process for each of the types of image data different in image structure, but a construction with such a device will not only require a large system, but will also entail an increase in cost.
Further, the construction of the image processing apparatus disclosed in Japanese Patent Unexamined Publication No. Hei. 5-108812 will be able to perform a rotating process without taking any recourse to any image structure, provided that the image processing apparatus is designed in such a manner as to perform a rotating process by writing one pixel after another of the image data having any image structure in a range not exceeding the data width in the buffer memory devices 207 and 208, but, in such a case, this construction will present a problem in that the image processing apparatus needs an extended length of time for its performance of a rotating process in the event that the image data are in a large amount of data because the processing velocity is determined by the number of pixels in the input data.
Furthermore, with the image processing apparatus disclosed in Japanese Patent Unexamined Publication No. Hei. 5-108812, it is conceivable to perform a rotating process by executing a writing/reading operation with a plural number of pieces of pixel data packed in a data width in the buffer memory devices 207 and 208, but, in such a case, the number of the patterns to be used in the processing of a rearranging operation of the image data read out of the buffer memory devices 207 and 208 will be the number obtained by (the number of modes of the angle of rotation.times.the number of image structures to be subjected to a rotating process), so that the construction of the image processing apparatus not only necessarily involves greater complexity in its processing operations but also inevitably requires a larger scale in its circuitry.